Method and apparatus for reporting performance of terminal in mobile communication system

ABSTRACT

A method for reporting performance of a terminal in a mobile communication system includes the steps of receiving a request for performance reporting from a base station, determining an indicator of whether a delay time related operation that the terminal supports is in correspondence with the request which corresponds to a pre-set condition, and transmitting a message including the determined indicator to the base station. The size of the performance reporting message may be minimized in reporting the performance of the terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 15/888,726,filed Feb. 5, 2018, which is a continuation of application Ser. No.14/434,380, which is the National Stage of International PatentApplication No. PCT/KR2013/009010, filed Oct. 8, 2013, now U.S. Pat. No.9,888,478, which claims priority to Korean Patent Application No.10-2012-0111458, filed Oct. 8, 2012, Korean Patent Application No.10-2012-0124355, filed Nov. 5, 2012, Korean Patent Application No.10-2012-0128393, filed Nov. 13, 2012, and Korean Patent Application No.10-2013-0037676, filed Apr. 5, 2013, the disclosures of which areincorporated herein by reference into the present disclosure as if fullyset forth herein.

BACKGROUND 1. Field

The present invention relates to a method and apparatus for reportingterminal capability in a mobile communication system.

2. Description of Related Art

Mobile communication systems were developed to provide mobile users withcommunication services. With the rapid advance of technologies, themobile communication systems have evolved to the level capable ofproviding high speed data communication service beyond the earlyvoice-oriented services.

Recently, standardization for a Long Term Evolution (LTE) system, as oneof the next-generation mobile communication systems, is underway in the3^(rd) Generation Partnership Project (3GPP). LTE aims at commercialdeployment around 2010 timeframe and realizing high-speed packet-basedcommunications with the data rate of up to 100 Mbps, which is higherthan the currently available data rate, and its standardization isalmost complete. In line with the completion of the LTE standardization,an LTE-Advanced (LTE-A) system is now under discussion, which improves atransfer rate by combining the LTE communication system with several newtechnologies. The term LTE system as used herein may be construed toinclude the legacy LTE system and the LTE-A system. The term ‘LTEsystem’ as used herein may be construed to include the legacy LTE systemand the LTE-A system. One of the representative technologies that arenewly adopted is Carrier Aggregation. The carrier aggregation is for aterminal to transmit/receive data over multiple carriers. In moredetail, the terminal transmits/receives data through predetermined cells(typically, the cells belonging to one base station) and this can beunderstood that the terminal transmits/receives data through multiplecells.

Multiple Input Multiple Output (MIMO) is another newly introducedtechnology.

The present invention proposes a method of reporting the terminalcapability information related to the newly introduced technologies tothe base station efficiently so as to facilitate communication betweenthe base station and the terminal.

SUMMARY

The present invention aims to provide a method and apparatus forreporting terminal capability using frequency band indicators havingdifferent formats.

In accordance with an aspect of the present invention, a capabilityreport method of a terminal in a mobile communication system includesreceiving a capability report request from a base station, determiningan indicator indicating whether a delay time-related operation supportedby the terminal fulfils a predetermined condition in response to therequest, and transmitting a message including the determined indicatorto the base station.

In accordance with another aspect of the present invention, a terminalcapability report reception method of a base station in a mobilecommunication system includes transmitting a capability report requestto a terminal and receiving a message including an indicator determineddepending on whether a delay time-related operation supported by theterminal fulfils a predetermined condition from the terminal.

In accordance with another aspect of the present invention, a terminalfor reporting capability in a mobile communication system includes atransceiver which transmits and receives signals to and from a basestation and a controller which controls the transceiver to receive acapability report request from the base station, determines an indicatorindicating whether a delay time-related operation supported by theterminal fulfils a predetermined condition in response to the request,and controls the transceiver to transmit a message including thedetermined indicator to the base station

In accordance with still another aspect of the present invention, a basestation for receiving terminal capability report in a mobilecommunication system includes a transceiver which transmits and receivessignals to and from a terminal and a controller which controls thetransceiver to transmit a capability report request to a terminal andreceive a message including an indicator determined depending on whethera delay time-related operation supported by the terminal fulfils apredetermined condition from the terminal.

The present invention is advantageous in terms of minimizing the size ofthe capability report message transmitted by the terminal.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating the architecture of an LTE system towhich the present invention is applied.

FIG. 2 is a diagram illustrating a protocol stack of the LTE system towhich the present invention is applied.

FIG. 3 is a diagram illustrating frequency band combination informationof the first embodiment.

FIG. 4 is a diagram illustrating overall operation of the firstembodiment.

FIG. 5 is a flowchart illustrating UE operation according to the firstembodiment.

FIG. 6 is a diagram for explaining carrier aggregation

FIG. 7 is a flowchart illustrating UE operation according to the secondembodiment.

FIG. 8 is a flowchart illustrating another UE operation according to thesecond embodiment.

FIG. 9 is a flowchart illustrating UE operation according to the thirdembodiment.

FIG. 10 is a block diagram illustrating a UE.

FIG. 11 is a block diagram illustrating a base station.

FIG. 12 is a flowchart illustrating another UE operation related to theSCell activation.

FIG. 13 is a diagram illustrating signal transmission/reception forsubframe determination according to an embodiment.

FIG. 14 is a flowchart illustrating UE operation according to the fourthembodiment of the present invention.

FIG. 15 is a diagram illustrating the architecture of the 3GPP LTEsystem according to an embodiment of the present invention.

FIGS. 16A and 16B are flowcharts illustrating a cell reselectionprocedure of the LTE/LTE-A system according to an embodiment of thepresent invention.

FIG. 17 is a signal flow diagram illustrating a de-prioritizationprocedure according to an embodiment of the present invention.

FIG. 18 is a flowchart illustrating a de-prioritization procedureaccording to another embodiment of the present invention.

FIG. 19 is a diagram illustrating an inter-band combination according toan embodiment of the present invention.

FIG. 20 is a diagram illustrating a format of supportedBandCombination2005 according to an embodiment of the present invention.

FIG. 21 is a diagram illustrating a structure of supported bandcombination information according to an embodiment of the presentinvention.

FIG. 22 is a diagram illustrating a structure ofsupportedBandCombination according to an embodiment of the presentinvention.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention are described withreference to the accompanying drawings in detail.

Descriptions on the technical details well-known in the art and notrelated directly to the present disclosure are omitted herein. This aimsto omit unnecessary description so as to make the subject matter of thepresent invention clear.

For the same reason, some of elements are exaggerated, omitted orsimplified in the drawings and the elements may have sizes and/or shapesdifferent from those shown in drawings, in practice. The same referencenumbers are used throughout the drawings to refer to the same or likeparts.

Detailed description of well-known functions and structures incorporatedherein may be omitted to avoid obscuring the subject matter of thepresent invention. Exemplary embodiments of the present invention aredescribed hereinafter with reference to the accompanying drawings. Abrief description is made of the LTE system before beginning theexplanation of the present invention.

FIG. 1 is a diagram illustrating the architecture of an LTE system towhich the present invention is applied.

As shown FIG. 1, the radio access network of the LTE system includesevolved Node Bs (eNBs) 105, 110, 115, and 120, a Mobility ManagementEntity (MME) 125, and a Serving-Gateway (S-GW) 130. The User Equipment(hereinafter, referred to as UE) 135 connects to an external network viathe eNBs 105, 110, 115, and 120 and the S-GW 130.

In an embodiment, the eNBs 105, 110, 115, and 120 correspond to thelegacy node Bs of the UMTS system. The eNBs 105, 110, 115, and 120 allowthe UE 135 to establish a radio channel and are responsible forfunctions more complicated as compared to the legacy node B. In the LTEsystem, all the user traffic services including real time services suchas Voice over Internet Protocol (VoIP) are provided through a sharedchannel and thus there is a need of a device to schedule data based onthe state information (such as buffer status, power headroom status, andchannel condition of the UE), the eNBs 105, 110, 115, and 120 beingresponsible for such functions. Typically, one eNB controls a pluralityof cells. In order to secure the data rate of up to 100 Mbps, the LTEsystem adopts Orthogonal Frequency Division Multiplexing (OFDM) as aradio access technology. Also, the LTE system adopts Adaptive Modulationand Coding (AMC) to determine the modulation scheme and channel codingrate in adaptation to the channel condition of the UE. The S-GW 130 isan entity to provide data bearers so as to establish and release databearers under the control of the MME 125. The MME 125 is responsible formobility management of UEs and various control functions and may beconnected to a plurality of eNBs.

FIG. 2 is a diagram illustrating a protocol stack of the LTE system towhich the present invention is applied.

Referring to FIG. 2, the protocol stack of the LTE system includesPacket Data Convergence Protocol (PDCP) 205 and 240, Radio Link Control(RLC) 210 and 235, Medium Access Control (MAC) 215 and 230, and Physical(PHY) 220 and 225. The PDCP 205 and 240 is responsible for IP headercompression/decompression, and the RLC 210 and 235 is responsible forsegmenting the PDCP Protocol Data Unit (PDU) into segments inappropriate size for Automatic Repeat Request (ARQ) operation. The MAC215 and 230 is responsible for establishing connection to a plurality ofRLC entities so as to multiplex the RLC PDUs into MAC PDUs anddemultiplex the MAC PDUs into RLC PDUs. The PHY 220 and 225 performschannel coding on the MAC PDU and modulates the MAC PDU into OFDMsymbols to transmit over radio channel or performs demodulating andchannel-decoding on the received OFDM symbols and delivers the decodeddata to the higher layer.

First Embodiment

The first embodiment of the present invention proposes a method andapparatus for minimizing the signaling overhead caused by extending thefrequency band indicator.

The frequency band indicator is the indicator of indicating thefrequency band and has a value in the range from 1 to 64 currently. Therelationship between the currently defined frequency band indicators andthe frequency bands are sorted out in table 1.

TABLE 1 E- UTRA Downlink (DL) operating Oper- Uplink (UL) operatingbandBS Du- ating bandBS receiveUE transmit transmit UE receive plex BandF_(UR) _(—) _(low)-F_(UL) _(—) _(high) F_(DL) _(—) _(low)-F_(DL) _(—)_(high) Mode  1 1920 MHz-1980 MHz 2110 MHz-2170 MHz FDD  2 1850 MHz-1910MHz 1930 MHz-1990 MHz FDD  3 1710 MHz-1785 MHz 1805 MHz-1880 MHz FDD  41710 MHz-1755 MHz 2110 MHz-2155 MHz FDD  5 824 MHz-849 MHz 869 MHz-894MHz FDD  6¹ 830 MHz-840 MHz 875 MHz-885 MHz FDD  7 2500 MHz-2570 MHz2620 MHz-2690 MHz FDD  8 880 MHz-915 MHz 925 MHz-960 MHz FDD  9 1749.9MHz-1784.9 MHz 1844.9 MHz-1879.9 MHz FDD 10 1710 MHz-1770 MHz 2110MHz-2170 MHz FDD 11 1427.9 MHz-1447.9 MHz 1475.9 MHz-1495.9 MHz FDD 12699 MHz-716 MHz 729 MHz-746 MHz FDD 13 777 MHz-787 MHz 746 MHz-756 MHzFDD 14 788 MHz-798 MHz 758 MHz-768 MHz FDD 15 Reserved Reserved FDD 16Reserved Reserved FDD 17 704 MHz-716 MHz 734 MHz-746 MHz FDD 18 815MHz-830 MHz 860 MHz-875 MHz FDD 19 830 MHz-845 MHz 875 MHz-890 MHz FDD20 832 MHz-862 MHz 791 MHz-821 MHz FDD 21 1447.9 MHz-1462.9 MHz 1495.9MHz-1510.9 MHz FDD 22 3410 MHz-3490 MHz 3510 MHz-3590 MHz FDD 23 2000MHz-2020 MHz 2180 MHz-2200 MHz FDD 24 1626.5 MHz-1660.5 MHz 1525MHz-1559 MHz FDD 25 1850 MHz-1915 MHz 1930 MHz-1995 MHz FDD 26 814MHz-849 MHz 859 MHz-894 MHz FDD 27 807 MHz-824 MHz 852 MHz-869 MHz FDD28 703 MHz-748 MHz 758 MHz-803 MHz FDD . . . 33 1900 MHz-1920 MHz 1900MHz-1920 MHz TDD 34 2010 MHz-2025 MHz 2010 MHz-2025 MHz TDD 35 1850MHz-1910 MHz 1850 MHz-1910 MHz TDD 36 1930 MHz-1990 MHz 1930 MHz-1990MHz TDD 37 1910 MHz-1930 MHz 1910 MHz-1930 MHz TDD 38 2570 MHz-2620 MHz2570 MHz-2620 MHz TDD 39 1880 MHz-1920 MHz 1880 MHz-1920 MHz TDD 40 2300MHz-2400 MHz 2300 MHz-2400 MHz TDD 41 2496 MHz-2690 MHz 2496 MHz-2690MHz TDD 42 3400 MHz-3600 MHz 3400 MHz-3600 MHz TDD 43 3600 MHz-3800 MHz3600 MHz-3800 MHz TDD 44 703 MHz-803 MHz 703 MHz-803 MHz TDD

The frequency bands 1 to 32 are designated for FDD, and the frequencybands 33 to 64 for TDD. In the table, the FDD frequency band indicatorsup to 28 are already in use and the rest of available indicators arepredicted to be exhausted in the near feature, and thus there is a needof extending the frequency band indicators up to 128.

The simplest way of expending the frequency band indicators is to definenew frequency band indicators with the values in the range from 1 to128. By taking notice that the values 1 from 64 are already being usedas the legacy frequency band indicators, this approach may causeinefficiency of wasting the values in the newly defined range.

In the present invention, it is propose to define the range of the newfrequency band indicators from 65 to 128 other than from 1 to 128. Inorder to distinguish between the frequency band indicator in the rangefrom 1 to 64 (hereinafter, referred to as type 1 frequency bandindicator) and the frequency band indicator in the range from 65 to 128(hereinafter, referred to as type 2 frequency band indicator) in usingthe frequency band for a certain purpose, separate information is used.

The frequency band indicators are used for various purposes as follows.

-   -   For UE to report frequency band it supports in the network    -   For UE to report frequency band combinations it supports in the        network    -   For network to inform UE of frequency band of current cell    -   For network to inform UE of frequency band of neighboring cell

In all the cases with the exception of the second case, a frequency bandis indicated by one of the type 1 frequency band indicator or the type 2frequency band indicator in one information element. In the second case,a band combination may include a range 1 frequency band (frequency bandindicated by the type 1 frequency band indicator. Frequency bandindicated by one of the frequency band indicators 1 to 64) and a range 2frequency band (frequency band indicated by the type 2 frequency bandindicator. Frequency and indicated by one of the frequency bandindicators equal to or greater than 65) and, at this time, both the type1 frequency band indicator and type 2 frequency band indicator have tobe used in the signal band combination. The band combinations can besorted as follows.

-   -   Band combination including only range 1 frequency bands    -   Band combination including range 1 frequency band and range 2        frequency band    -   Band combination including only range 2 frequency bands

In the present invention, the type 1 frequency band combinationinformation is used for the first case, the type 2 frequency bandcombination information for the second case, and the type 3 frequencycombination information for the third case. Whether certain frequencyband combination information is the type 1 frequency band combinationinformation, type 2 frequency band combination information, or type 3frequency band combination information can be identified by tagging a1-bit or 2-bit information to the frequency band combinationinformation. For example, the frequency band combination informationwithout combination information discrimination information may beidentified as the type 1 frequency band combination information, whilethe frequency band combination information with combination informationdiscrimination information may be identified as the type 2 frequencyband combination information or type 3 frequency band combinationinformation.

The frequency band combination information includes at least onefrequency band indicator and per-frequency band UE capabilityinformation. The frequency band combination information is referencedwhen the eNB configures carrier aggregation to the UE afterward.

If the frequency band combination information has no combinationinformation discrimination information 305, this means the type 1frequency band combination information, and the frequency bandindicators 310 and 315 included in the information are the type 1frequency band indicators having the values in the range from 1 to 64.For example, ‘000000’ indicates band 1, and ‘111111’ indicates band 64.

If the frequency band combination information has the combinationinformation discrimination information 325 set to a predetermined value,the frequency band combination information is the type 3 frequency bandcombination information 320, and the frequency band indicators 330 and335 including the information are type 2 frequency band indicators withvalues in the range from 65 to 128. For example, ‘000000’ indicates band65, and ‘111111’ indicates band 128.

If the frequency band combination information has the combinationinformation discrimination information 345 which is set to anotherpredetermined value, the frequency band combination information is thetype 2 frequency band combination information 340 and, in this case, thefrequency band indicators 350 and 355 included in the information mayindicates the bands in formats different from the type 1 frequency bandindicator and type 2 frequency band indicator. For example, UE may tagsa bit indicating whether the frequency band indicator included in thetype 2 frequency band combination information indicates the range 1frequency band or the range 2 frequency band to the band indicationinformation. Here, the frequency band indicator tagged with theinformation indicating whether the frequency band is the range 1frequency band or the range 2 frequency band is referred to as type 3frequency band indicator. If the first bit (Most Significant Bit (MSB)of the type 3 frequency band indicator is 0, the rest 6 bits indicatethe range 1 frequency band and, otherwise if the first bit is 1, therest 6 bits indicate the range 2 frequency band. Accordingly, thefrequency band indicator included in the type 2 frequency bandcombination information (i.e. type 3 frequency band indicator) has asize longer as much as 1 bit than the frequency band indicator includedthe type 1 or type 3 frequency band combination information (i.e. type 1frequency band indicator or type 2 frequency band indicator). In anotherway, it can be considered to define shortened information of thefrequency band indicator applied commonly to the range 1 frequency bandsand range 2 frequency bands instead of inserting the frequency bandindicator into the type 2 frequency band combination information. Bytaking notice that the number of frequency bands supported by one UE isvery less than the 64 or 128, it is possible to further reduce thesignaling overhead using the shortened information. The shortened bandindicator can be defined as follows.

The information on the frequency band combinations supported by the UEis transmitted using the UE capability report message. The capabilityreport message includes the information on the frequency bands in theform of ‘supportable frequency band list’ as well as the frequency bandcombinations supported by the UE. The supportable frequency band listmay be divided into a type 1 supportable frequency band list and a type2 supportable frequency band list. The type 1 supportable frequency bandlist contains the range 1 frequency bands, and the type 2 supportablefrequency band list contains the range 2 frequency bands. Assuming thatthe type 1 frequency band list includes n range 1 frequency bands, theUE allocates the shortened indicators 0 to [n−1] in the order ofinsertion of the range 1 frequency bands. Assuming that the type 2frequency band list includes m range 2 frequency bands, the UE allocatesthe shortened indicators n to [n+,+1] in the order of insertions of therange 2 frequency band. The UE informs of the corresponding frequencyband in the range 2 frequency band combination information using theshortened indicator. The length of the shortened indicator may be set inconsideration of the maximum number of frequency bands that UE cansupport. In the present invention, the length of the shortened indicatoris 4 bits.

For example, a certain UE may support the range 1 frequency bands 2, 65,and 67, and the frequency band combinations [1,2], [1,65], [2,65], and[65,67].

The UE includes the information corresponding to the range 1 and range 2frequency bands, i.e. 000000 and 000001, in the supportable type 1frequency band list.

The UE includes the information corresponding to frequency bands 65 and67, i.e. 000000 and 000001, in the supportable type 2 frequency bandlist.

The UE allocates 0000 as the shortened indicator for the frequency band1, 0001 as the shortened indicator for the frequency band 2, 0010 as theshortened indicator for frequency band 3, and 0011 for frequency band 4.

The UE includes the shortened indicator combinations corresponding tothe frequency band combinations [1,65] and [2,65], i.e. [0000, 0010] and[0001, 0010], in the type 2 frequency band combination information.

Although since the type 1 frequency band combination information is usedby the previous release eNB the frequency band has to be indicated usingthe frequency band indicator as before, the shortened indicator, otherthan the type 2 frequency band indicator, can be used for the type 3frequency band combination information. In this case, the type 3frequency band combination information includes the combination ofshortened indicators [0010, 0011].

FIG. 4 shows the UE operation.

FIG. 4 shows the overall operation of the present invention.

In the mobile communication system including a UE 405, an eNB 410, andan MME 415, the UE powers on at step 420. The UE performs a cell searchprocedure to find cells and PLMNs and determines the PLMN and cell toperform a registration procedure based on the cell search result at step425.

The UE performs a RRC Connection Setup procedure through the selectedcell and sends the MME an ATTACH REQUEST message to request forregistration at step 430. This message includes the UE identifier.

If the ATTACH REQUEST message is received, the MME determines whether toaccept the UE attachment and, if it is determined to accept, sends theserving eNB of the UE a control message called Initial Context SetupRequest at step 435. If the UE has the UE capability information, the UEcapability information may be included in the control message; however,the MME has no such information in the initial attachment procedure andthus the control message includes no UE capability information.

If the Initial Context Setup Request message including no UE capabilityinformation is received, the eNB sends the UE a control message calledUE CAPABILITY ENQUIRY at step 440. This message is of requesting the UEto report capability such as Radio Access Technology (RAT) capabilityinformation using the parameter called RAT Type. If the UE is performingthe above procedure in the LTE network, the RAT Type is set to EvolvedUniversal Terrestrial Radio Access (E-UTRA). If there is other radionetwork, e.g. UMTS network, around, the eNB may request the UE for theUMTS capability information too by adding UTRA to the RAT Type.

If the UE CAPABILITY ENQUIRY message is received, the UE generates UECAPABILITY INFORMATION including its capability information about theradio technology indicated by the RAT Type. The control message includesa list of the frequency bands supported by the UE and the information onthe frequency band combinations supported by the UE. The UE generatesthe type 1 frequency band list including the frequency bands representedby the frequency band indicators 1 to 64 and the type 2 frequency bandlist including the frequency bands represented by the frequency bandindicators 65 to 128. The UE reports the combinations of the frequencybands in the range of the frequency band indicators 1 to 64 using thetype 1 frequency band indicator in the type 1 frequency band combinationinformation, combinations of the frequency bands in the range of thefrequency band indicators 65 to 128 using the type 2 frequency bandindicators in the type 3 frequency band combination information, and thecombinations of the frequency band in the range of the frequency bandindicators 1 to 64 and the frequency band in the range of the frequencyband indicators 65 to 128 using the shortened indicator in the type 2frequency band combination information. It is also possible to includethe type 3 frequency band combination information in the type 2frequency band combination information. That is, in the cases with theexception of the combination of the frequency bands in the range of thefrequency band indicators 1 to 64 (i.e. all combination of the frequencybands in the rage of the frequency band indicators 65 to 128) isreported using the shortened indicator in the type 2 frequency bandcombination information. In this case, the UE reports only the type 1frequency band combination information and type 2 frequency bandcombination information.

The UE sends the eNB A UE CAPABILITY INFORMATION message at step 445.The eNB sends the MME a UE CAPABILITY INFO INDICATION message to reportthe UE capability information included in the UE CAPABILITY INFORMATIONmessage to the MME at step 450. The eNB performs reconfiguration to theUE by referencing the UE traffic status and channel condition based onthe capability information reported by the UE. For example, if it isreported that the UE has to communicate large amount of data and the UEsupports frequency band aggregation, the eNB configures additionalcarrier (i.e. configured multiple serving cells) to increase the datarate at step 455. The UE performs reconfiguration as commanded by theeNB at step 460 and performs the normal communication procedure.

FIG. 5 shows the UE operation.

If the UE CAPABILITY ENQUIRY message is received at step 505, the UEchecks the RAT Type at step 510. If the RAT Type is set to E-UTRA, theprocedure goes to step 520 and, otherwise the RAT Type is set othervalue than E-UTRA, step 515. At step 515, the UE operates according tothe conventional technology. At step 520, the UE transmits the UECAPABILITY INFORMATION message including its LTE capability information.The LTE capability information includes the information as follows.

-   -   Type 1 frequency band list and type 1 frequency band combination        information are included when the UE supports only the range 1        frequency bands (bands in the range 1 through 64).    -   Type 1 frequency band list, type 2 frequency band list, type 1        frequency band combination information, type 2 frequency band        combination information, and type 3 frequency band combination        information are included, when the UE support at least one of        range 2 frequency bands (bands in the range 65 through 128).

Second Embodiment

In order to increase UE data rate, a technique called carrieraggregation for aggregating multiple serving cells for one UE.

FIG. 6 is a diagram for explaining carrier aggregation.

Referring to FIG. 6, an eNB transmits and receives signals throughmultiple carriers across a plurality of frequency bands. For example,when the eNB 605 is configured to use the carrier 615 with centerfrequency at f1 and the carrier 610 with center frequency at f3, thelegacy UE transmits/receives data using one of the two carriers.However, the carrier aggregation-enabled UE can transmit/receive datausing multiple carriers. The eNB 605 can increase the amount of theresource to be allocated to the carrier aggregation-enabled UE inadaptation to the channel condition of the UE so as to improve the datarate of the UE 630. This technique of aggregating the downlink carriersor uplink carriers at the eNB is called carrier aggregation.

The terms that are used frequently in the following description aredefined below.

Assuming that a cell is configured with one downlink carrier and oneuplink carrier in the conventional concept, the carrier aggregation canbe understood as if the UE communicates data through multiple cells.With the use of carrier aggregation, the peak data rate increases inproportion to the number of aggregated carriers.

In the following description, if a UE receives data through a certaindownlink carrier or transmits data through a certain uplink carrier,this means the UE transmits/receives data through a control channel anda data channel provided by the cell corresponding to the centerfrequency and frequency band characterizing the carrier. In the presentinvention, the carrier aggregation can be expressed like this ‘aplurality of serving cells are configured’ along with the use of theterms ‘Primary Serving cell (PCell),’ ‘Secondary Serving cell (SCell),’‘activated service cell,’ etc. These terms are used in the same meaningsas those used in the LTE mobile communication system and specified inTS36.331 and TS36.321. In the present invention, the termstimeAlignmentTimer, Activation/Deactivation MAC Control Element, C-RNTIMAC CE are used in the meanings as specified in TS36.321.

If a certain SCell is activated, the UE operates as follows.

[Activation Operation]

-   -   Transmit SRS if Sounding Reference Signal (SRS) transmission is        configured for corresponding SCell    -   Report Channel Quality Indicator/Precoding Matrix Indicator/Rank        Indicator/Precoding Type Indicator (CQI/PMI/RI/PTI) for        corresponding SCell: The CQI/PMI/RI/PTI for an SCell is the        information for channel condition and MIMO operation of the        corresponding SCell, and the UE determines CQI/PMI/RI/PTI based        on the measurement value to the corresponding SCell and        transmits the CQI/PMI/RI/PTI on PUCCH of the PCell. If        CQI/PMI/RI/PTI for certain SCell is configured and if the SCell        is activated, the SCell performs reporting the CQI/PMI/RI/PTI        using the PUCCH transmission resource (or in a predetermined        PUCCH format) of the PCell which is allocated for CQI/PMI/RI/PTI        transmission.    -   Start monitoring PDCCH of corresponding SCell: If inter-carrier        scheduling is not configured for the corresponding SCell        (scheduling information for predetermined SCell is transmitter        to the UE through the PDCCH of other SCell than the PDCCH of the        corresponding SCell. may be configured by eNB), the UE monitors        PDCCH of the activated SCell.    -   Start monitoring PDCCH of corresponding SCell: If inter-carrier        scheduling is configured for the corresponding SCell, the UE        monitors the PDCCH of the serving cell to which activated SCell        scheduling information transmission is configured to receive the        SCell scheduling information.

If a certain SCell is deactivated, the UE stops the above operation.That is, the UE stops transmitting SRS, reporting CQI/PMI/RI/PTI,monitoring PDCCH of SCell, and monitoring PDCCH for SCell.

The activation and deactivation of the SCell is triggered by receivingan Activation/Deactivation MAC Control Element (A/D MAC CE). The A/D MACCE is the control information of 8-bit bitmap of which bits are mappedto the SCells configured to the UE. The UE activates or deactivates theSCells according to the corresponding bits of the bitmap.

If an A/D MAC CE for activating or deactivating a certain SCell isreceived at a certain subframe, the UE and the eNB have to perform theactivation or deactivation operation at the same timing. However, thetime required for perform the activation or deactivation operation maychange depending on the UE capability and the condition of the SCell tobe activated. Particularly if the Radio Frequency Frontend for the SCellto be activated is in the activated state already, it may take a shorttime to complete the SCell activation and, otherwise if the RadioFrequency Frontend for the SCell to be activated is in the deactivatedstate, it may take a long time to complete the SCell activation becauseit is necessary to activate the Radio Frequency Frontend first. Forexplanation convenience, the time required for activating the SCell inthe case that the Radio Frequency Frontend for the SCell is activatedalready (i.e. the activated Radio Frequency Frontend covers thefrequency band of the SCell) is referred to as activation delay 1, andthe time required for activating the SCell in the case that the RadioFrequency Frontend for the SCell is not activated is referred to asactivation delay 2.

Typically, the eNB does not know which Radio Frequency Frontend the UEuses for a curtained SCell and thus cannot determine whether the UE usesthe activation delay 1 or activation delay 2 when the SCell isactivated.

The present invention proposes a method for the UE and the eNB to applythe same activation delay according to a predetermined rule. The rule ofdetermining the activation delay is as follows.

[Activation Delay Determination Rule 1]

In the case of activating a SCell x, if another serving cell(hereinafter, serving cell y) using the same frequency band as the SCellx is activated already, the activation delay 1 is used and, otherwise,activation delay 2 is used.

If there is a serving cell activated already on the same frequency bandas the SCell to be activated, this means that the Radio FrequencyFrontend for the frequency band of the SCell to be activated is in theactive state. In this case, it is preferred to apply the activationdelay 1.

[Activation Delay Determination Rule 2]

In the case of activating a SCell x, if serving cell (hereinafter,serving cell y) using the same frequency band as the SCell x isactivated already and if the frequency of the serving cell y is aneighboring frequency of the frequency of the SCell x, the activationdelay 1 is used and, otherwise (i.e. if at least one of the twoconditions is not fulfilled), the activation delay 2 is used.

Although the serving cell y and the SCell x are on the same frequencyband, if the two cells are not neighboring in the frequency domain (i.e.the frequencies of the two cells are not contiguous or non-continuous),different Radio Frequency Frontends may be used for the two cells. Inthis case, although there is a cell activated on the same frequencyband, a new Radio Frequency Frontend is activated for the SCell x andthus the activation delay 2 is used.

[Activation Delay Determination Rule 3]

In the case of activating a SCell x, if serving cell (hereinafter,serving cell y) using the same frequency band as the SCell x isactivated already, if the frequency of the serving cell y is aneighboring frequency of the frequency of the SCell x, if ‘deactivatedstate measurement cycle’ of the SCell x is equal to or less than apredetermined threshold value, the activation delay 1 is used and,otherwise (i.e. if at least one of the three conditions is notfulfilled), the activation delay 2 is used.

The deactivated state measurement cycle is a parameter configured perfrequency to determine the SCell measurement frequency of the UE when aSCell is configured on the corresponding frequency and the SCell isdeactivated. The reason for deactivating the SCell is to minimize thepower consumption. If the measurement to the deactivated SCell isperform too frequently, this makes it difficult to achieve the powerconsumption minimization and thus the ‘deactivated state measurementcycle’ is configured to control the measurement frequency to anappropriate level.

If the deactivated state measurement cycle for the SCell x is equal toor less than a predetermined threshold value, adjusting the bandwidth ofthe Radio Frequency Frontend once at every deactivated state measurementcycle may cause bad influence to the data communication through theserving cell y and thus it is preferred to maintain the Radio FrequencyFrontend although the SCell x is deactivated. In this case, since theRadio Frequency Frontend is activated already, when activating the SCellx, the activation delay 1 is applied.

Otherwise if the deactivated state measurement cycle for the SCell x isgreater than the predetermined threshold value, the bandwidth of theRadio Frequency Frontend is adjusted to do not include the SCell x, whenthe SCell x is deactivated, to minimize the power consumption.Accordingly, when the SCell x is activated again, the bandwidth of theRadio Frequency Frontend has to be readjusted and this operation isalmost similar to activating the Radio Frequency Frontend and thus theactivation delay 2 is applied.

[Activation Delay Determination Rule 4]

When configuring a certain SCell, the eNB determines the activationdelay to be applied to the UE. The configuration information of theSCell includes the activation delay length information and, whenactivating the SCell x, the UE applies a suitable activation delay byreferencing whether the activation delay length information is of theactivation delay 1 or of the activation delay 2.

In case of activating the SCell x, if the activation delay 1 (or 2) isapplied, this means that when the A/D MAC CE for activating the SCell xis received at subframe n the SCell x activation operation starts at thesubframe [n+activation delay 1 (or 2)].

FIG. 7 is a flowchart illustrating the UE operation of the thirdembodiment.

Referring to FIG. 7, the UE reports its capability to the eNB at step705. At this time, the UE reports the frequency bands and frequency bandcombinations for carrier aggregation, which it supports, along withnecessity of Radio Frequency Frontend activation for intra-bendcombination, if any, in the frequency band combinations. For example,the UE supports frequency bands x and y and frequency band combinationsfor carrier aggregation as shown in table 2.

TABLE 2 Radio Frequency Frontend activation Band combination necessityFrequency band 1 serving cell on band x NO combination 1 Frequency band1 serving cell on band y NO combination 2 Frequency band 2 serving cellson band x YES combination 3 Frequency band 2 serving cells on band y YEScombination 4 Frequency band 1 serving cell on band NO combination 5 x,1 serving cell on band y Frequency band 2 serving cells on band YEScombination 6 x, 1 serving cell on band y

The UE sends 1-bit information to report the Radio Frequency Frontendactivation necessity for the frequency band fulfilling the followingcondition.

Band Combination Having at Least Two Serving Cells on One Band

In the above example, the frequency band combination 3 is configuredwith two serving cells on the band x such that the radio frequencyfrontend activation necessity is reported. If the radio frequencyfrontend activations is necessary for the band combination having atleast two serving cell, this means that when at least one serving cellis in the activated state, the radio frequency frontend has to beactivated when the other cell is activated (i.e., different radiofrequency frontends are used for the two serving cells).

The UE receives a control message for configuring at least one SCell atstep 710. The control message includes the information on the centerfrequency, frequency band, and cell bandwidth of the SCell. The controlmessage also may include deactivated state measurement cycle to beapplied to the SCell. The control message also may include theinformation on whether to apply the activation delay 1 or activationdelay 2 to the SCell. The UE stores the information carried by controlmessage and performs a required reconfiguration operation.

The UE receives an A/D MAC CE for activating the SCell at subframe n atstep 715. That is, the UE receives the A/D MAC CE including the bitcorresponding to the SCell indicates ‘activation’ at subframe n. The UEdetermines whether the SCell is in the activated state already and, ifso, waits for receiving a new A/D MAC CE and, otherwise, the proceduregoes to step 720.

At step 720, the UE determines whether to apply the activation delay 1or activation delay 2 to determine the subframe for performingactivation of the SCell, i.e. transitioning from the deactivated stateto the activated state. At this time, an [activation delay determinationrule] is applied.

The UE performs the activation operation at the subframe determined inconsideration of the selected activation delay at step 725. That is, ifit is determined to apply the activation delay 1, the UE performs theactivation operation at subframe [n+activation delay 1] and, otherwiseif it is determined to apply the activation delay 2, at subframe[n+activation delay 2]. Alternatively, it can be considered to startpart of the activation operation in advance. As described above, theactivation delay is a kind of minimum requirement determined inconsideration of the UE capability. That is, a relatively long timevalue is set in order for the low capability UE to meet requirement.Accordingly, a high capability UE may complete preparation for theactivation before the activation delay. It is preferred for the UE tocomplete the operation in advance if pre-performing the operation doesnot cause any problem. For example, since the CQI/PMI/RI/PTI istransmitted through the activated PCell other the any SCell, it ispossible to transmit the information in advance before the activationdelay. It is also possible to start monitoring PDCCH for the SCellbefore the SCell is activated. Accordingly, in the case of activating aSCell, if the radio frequency frontend for the SCell is in the activatedstate already, the UE performs the whole activation operation atsubframe [n+activation delay 1] and, otherwise if the radio frequencyfronted for the SCell is not the activated state, performs theCQI/PMI/RI/PTI transmission and monitoring PDCCH for the SCell atsubframe [n+activation delay 1] and SRS transmission and SCell PDCCHmonitoring at subframe [n+activation delay 2].

FIG. 12 shows another UE operation related to the SCell activation.

The operation depicted in FIG. 12 can be summarized as follows. Asdescribed above, since the activation delay is determined inconsideration of the lowest capability UE, the high capability UE maycomplete reconfiguration of the radio frequency frontend before theactivation delay lapses. If such a UE is not scheduled until theactivation delay lapses, this may cause a problem of degrading the UEcapability unnecessarily. The present invention proposes an approach ofdefining two timings in order for the UE to report the radio frequencyfrontend reconfiguration completion (or activation reparationcompletion) dynamically after the first timing. That is, if theactivation preparation is completed, the UE reports the activationpreparation completion to the eNB, which performs scheduling in theSCell upon receipt of the completion signal. The second timing is of theactivation delay in the typical meaning, and every UE has to completethe radio frequency front end reconfiguration and activation preparationat least until the lapse of the second timing.

The activation completion may be reported in various methods.

1) CSI report reflecting channel quality of activated SCell

2) SRS transmission in activated SCell

The eNB may configure per-SCell CSI report to the UE which istransmitted through the PCell. The eNB determines the cycle, timeduration, and transmission resource for the CSI report and notifies theUE of the related information. Since the transmission format of theother uplink transmission through the PCell, e.g. PUSCH and HARQfeedback transmission, may change depending on whether cis istransmitted, it is preferred to start CSI transmission at apredetermined timing. In the present invention, the UE starts CSItransmission through the SCell at the first timing in consideration ofthe above matters and, if it fails to perform SCell measurement, reportsthe CQI set to a predetermined value. Both the CSI and CQI are controlsignals related to the channel quality of a predetermined serving celland, although CSI has a broad meaning including CQI, the two terms areused interchangeably in the present invention unless otherwise stated.

The UE and the eNB start CQI transmission/reception at the first timing,and the timing of transmitting/receiving the CQI having a valuedifferent from a predetermined value can be determined as the timing ofinitiating various operations related to the activation.

The SRS transmission is performed through the corresponding SCell otherthan the PCell; and the eNB determines the SRS transmission cycle,transmission time duration, and transmission resource and notifies theUE of the determination result. Since the SRS transmission does notaffect other uplink transmissions in the PCell, there is no need tostart the SRS transmission in the state that the SRS transmission is notprepared completely. If the radio frequency frontend configuration forthe SCell is completed, the UE starts SRS transmission, and the UE andthe eNB determine the SRS transmission start timing as the timing forstarting various operations related to the activation.

The UE selects the subframe for starting the operation related to theactivation in consideration of both the subframe at which the CSItransmission starts and the subframe at which the SRS transmissionstarts. That is, the preceding timing among the two timings may bedetermined as the timing of starting the operations related to theactivation.

In summary, when activating a SCell x, the UE sorts theactivation-related operations as follows and perform the operations atcorresponding timings. Here, n denotes the subframe at which the A/D MACCE for activating the SCell x is received, and a and b are constantsindicating the subframes at which the UE starts transmitting the pseudoCSI. b is a constant related to the activation delay, and every UE hasto complete the operations related to the activation at least before b.x denotes the subframe related to the timing at which the UE completesthe radio frequency frontend reconfiguration.

Table 3 lists the operations, operation occurrence timings, anddescription thereof according to an embodiment

TABLE 3 SCell x activation-related operation Application timing NotesCellDeactivationTimer n + a or n + b sCellDeactivationTimer is a timerfor UE to start or restart deactivate SCell x autonomously when there isno scheduling during a predetermined period in SCell x. The start timepoint of this timer should be the predictable by the eNB and is one of aand be in the present invention. PHR trigger n + b or time when When aserving cell is activated, PHR is UL grant for SCell is triggered toprovide the UE transmit power received status in the serving cell. Atthis time, in order to include the useful information on the SCell asmuch as possible in the PHR, it is necessary to avoid triggering the PHRso promptly. In the present invention the PHR trigger time is set to n +b or time when PUSCH is transmitted fist in the SCell x. Pseudo CSItransmission n + a As described above, the CSI transmission start startsat a predetermined time. At this time, if the channel condition in theSCell is not checked yet, the UE transmits the CQI set to apredetermined value (e.g. 0000, out of range). Real CSI transmissionstart n + x As described above, the UE does not report the CSIreflecting the channel state of the SCell unit the radio frequencyfrontend reconfiguration is completed. The UE reports the CSI reflectingthe channel state of the SCell (hereinafter, real CSI) since thesubframe at which the radio frequency frontend reconfiguration iscompleted. x is an integer between a and b and variable depending on theUE capability and condition. SRS transmission start n + x As describedabove, if the radio frequency frontend reconfiguration is completed, theUE starts SRS transmission. PDCCH monitoring n + x If the radiofrequency frontend reconfiguration is completed, the UE startsmonitoring PDCCH for SCell x.

The UE operation is described hereinafter in detail with reference toFIG. 12.

Step 1205 is identical with step 705.

Step 1210 is similar to step 710, and the SCell configuration controlmessage may further include the following information.

PUCCH configuration information for CSI information transmission for theSCell x, CSI information transmission time duration information, CSItransmission resource information, etc.

SRS transmission resource information for SCell x; SRS transmission timeduration information, SRS transmission resource information, etc.

The UE receives an A/D MAC CE instructing activation of the SCell x atsubframe n at step 1215. That is, the A/D MAC CE including the bitcorresponding to the SCell x is set to 1 is received.

The UE controls a related entity to start the sCellDeactivationTimer ofthe SCell x at a predetermined time, e.g. n+a or n+b, at step 1220.

If uplink is configured to the SCell x, the UE controls the relatedentity to trigger PHR at a predetermined time.

The UE determines whether the SCell x activation is real activation atstep 1230 and, if so, the procedure goes to step 1240 and, otherwise,step 1235. If the SCell x activation is the real activation, this meansthat the A/D MAC CE instructing activation of the SCell in thedeactivated state. That is, the SCell x is in the deactivated statebefore step 1215. If the SCell x is not in the real activated state,this means that the A/D MAC CE instructing activation of the SCell whichis already in the activated state. The reason why the SCell is not inthe real activated state is because, since the A/D MAC CE includes theactivation/deactivation state informations on all the serving cellsconfigured to the UE, in order to transition the state of some servingcells among them from the deactivated state to the activated state it isnecessary to transmit the activation indication information to otherserving cells that are already in the activated cells too.

The UE continue monitoring PDCCH for the SCell x and transmitting CSIand SRS as before at step 1235.

The UE controls the transceiver to start CSI transmission for SCell xthrough the PCell at the time (n+a) at step 1240. If it fails todetermine the CQI to report for the SCell x, the UE reports apredetermined value, e.g. 0000. That is, it reports the CSI set to 0000at the time between n+a and n+x.

The UE controls the transceiver to start monitoring PDCCH, reportingreal CSI, and transmitting SRS at the time n+x at step 1245. Here, x isan integer indicating a subframe fulfilling the following conditions.

[Condition for Determining x]

Assuming the subframe at which the radio frequency frontendreconfiguration has been completed for the SCell x is x′, the UEdetermines subframe x among the subframes identical with or following x′and among CSI-related and SRS-related subframes. The CSI-related andSRS-related subframes are defined as follows.

[SRS-Related Subframe for SCell x]

subframe including SRS transmission duration of SCell x which arrivefirst since completion of radio frequency frontend reconfiguration forSCell x.

[CSI-Related Subframe for SCell x]

First subframe capable of transmitting CSI reflecting channel conditionof SCell x since completion of radio frequency frontend reconfigurationfor SCell x

Even when the UE reports the real CSI for the SCell x, there is still aprobability that CQI is set to 0000. In this case, although the UEreports the real CSI, the eNB cannot understand it and thus an error mayoccur between the UE and the eNB. In order to avoid this problem, theCSI-related subframe for SCell x may be defined as follows.

[CSI-Related Subframe for SCell x]

First subframe for reporting CQI not set to 0000 for SCell x sincecompletion of radio frequency frontend reconfiguration for SCell x

The CQI reported at subframe y is the value measured at subframe [y−4]or a predetermined subframe earlier. Accordingly, the real CSI report isdelayed as long as 4 subframes or longer since the completion of theradio frequency frontend reconfiguration. In order to avoid this, it maybe considered to do not apply the timing mapping relationship for theCQI being reported first since the completion of the radio frequencyfrontend reconfiguration. For example, if the radio frequency frontendreconfiguration is completed at [y−2], the UE measures the channelcondition of the SCell x. Although there is channel state value measuredat the timing (e.g. y−4) mapped to the above subframe in reporting CQIat subframe y, the UE reports the CQI with the channel state valuemeasured afterward (e.g. measured at [y−1]).

At step 1250, the UE checks whether the radio frequency frontendreconfiguration affects the PCell data transmission/reception and, ifso, performs reconfiguration during a predetermined period in which thePCell PDCCH monitoring and PCell uplink transmission are suspended.

The radio frequency frontend reconfiguration for activating SCell xaffects the PCell data transmission/reception in the follow case.

The frequency band of the SCell x is identical with the frequency bandof the PCell, and the frequency band of the radio frequency frontendprocessing the frequency band signal does not include the frequency ofthe SCell x yet.

In the above case, the radio frequency frontend which is responsible forthe PCell has to be configured to process the SCell x, and the PCelldata transmission/reception is suspended in part of the reconfigurationtime duration.

FIG. 13 is a diagram illustrating transmission/reception of the signalfor determining the subframe according to an embodiment of the presentinvention.

Referring to FIG. 13, assuming a=8 and b=24, the UE receives the A/D MACCE at subframe n as denoted by reference number 1305. The UE startsreconfiguring the radio frequency frontend and transmitting CQI at thefirst subframe having the CQI transmission resource among the subframessince a predetermined subframe, i.e. [n+8] as denoted by referencenumber 1310. The CQI is may be reported before the UE completesreconfiguration of the radio frequency frontend to measure the channelcondition for the SCell x.

If the RF frontend reconfiguration is completed at a certain time pointas denoted by reference number 1315 and then the SRS-related subframeoccurs prior to the CSI-related subframe, the UE transmits the SRS inthe SRS-related subframe as denoted by reference number 1320 anddetermines the subframe as subframe [n+x].

If the RF frontend reconfiguration is completed at another time point asdenoted by reference number 1325 and then the SRS-related subframeoccurs prior to the CSI-related subframe, the UE transmits the CSI asdenoted by reference number 1330 and determines the subframe as subframe[n+x].

The eNB sends the UE a control message called RRC ConnectionReconfiguration message for configuring a SCell, and the UE sends theeNB a response message.

The response message is transmitted for two main purposes in response tothe configuration message.

1. The UE transmits the response message to acknowledge the receipt ofthe configuration message and report the execution of the commandincluded in the configuration message to the eNB.

2. The UE transmits the response message to report the execution of thecommand included in the configuration message to the eNB.

If a SCell is configured or released (i.e. an RRC ConnectionReconfiguration message for configuring or releasing the SCell isreceived), the UE (re)configures the RF frontend according to theoperation. It takes more time to (re)configure the RF frontend ascompared to the other reconfiguration operation indicated by the RRCConnection Reconfiguration message. Accordingly, the time required forthe UE to complete necessary operation may vary depending on whether theRRC Connection Reconfiguration message includes the SCellconfiguration/release information.

If the eNB has commanded a predetermined reconfiguration, it isnecessary to receive the response message quickly. Accordingly, the eNBtries to allocate uplink transmission resource to the UE to receive theresponse message as soon as possible.

At this time, the eNB has to determine the timing for allocating thetransmission resource for receiving the response message since thetransmission of the RRC Connection Reconfiguration message.

For this purpose, the present invention specifies that the UE generatesthe response message after predetermined time duration since the receiptof the RRC Connection Reconfiguration to assist the scheduling operationof the eNB. At this time, the time duration is defined differently bytaking notice that the RRC Connection Reconfiguration message istransmitted for configuring or releasing the SCell. The configurationdelay 1 is applied for the RRC Connection Reconfiguration message withthe SCell configuration/release indicator, and the configuration delay 2for the RRC Connection Reconfiguration message without SCellconfiguration/release indicator. However, the RF frontend configurationmay be maintained in a certain case although the SCellconfiguration/release is instructed. This is the case when a new SCellis configured at the same time as a configured SCell is released on thesame frequency. The SCells on the same frequency may be released usingone control message and then reconfigured when reconfiguring theidentifiers of the SCells, updating system information for the SCells,and changing some parameters related to the SCells.

FIG. 8 shows the above UE operation.

Step 805 is identical with step 705.

The UE receives an RRC Connection Reconfiguration message at step 810.

The UE determines whether the RRC Connection Reconfiguration messageincludes SCell configuration/release command at step 815. If the messageincludes no SCell configuration/release command, the UE applies theconfiguration delay 2 at step 820.

Otherwise, if the message includes the SCell configuration/releasecommand, the UE determines whether at least one SCell is released and atleast one SCell is configured and whether the center frequencies andcell bandwidths of the released and configured SCells are identical witheach other at step 825. If all the conditions are fulfilled, theprocedure goes to step 820. Otherwise, at least one of the conditions isnot fulfilled, i.e. if only a SCell is configured or released or ifalthough a SCell is configured and a SCell is released the centerfrequencies and cell bandwidths of the released and configured cellsdiffer from each other, the UE applies the configuration delay 1 at step830.

If the configuration delay 1 or configuration delay 2 is applied, thismeans that the response message is ready to be transmitted in responseto the RRC Connection Reconfiguration message when the RRC ConnectionReconfiguration message is received at subframe n or when an uplinkgrant is received at subframe [n+configuration delay 1 or 2].

The configuration delays 1 and 2 may be to certain values inconsideration of the UE capability, and the configuration delay 1 has tohave a value greater than that of the configuration value 2 because itis determined in consideration of the extra delay for RF frontendreconfiguration.

Third Embodiment

With the popularization of smartphones, the requirements and uses ofwireless location area network (WLAN), Bluetooth, and GPS are increasingabruptly. In line with this tendency, a terminal integrates variouscommunication technologies (e.g. legacy cellular network technology(LTE/UMTS), WLAN, Bluetooth, and GNSS/GPS) which bring out interferenceproblem therebetween. This issue is discussed under the title ofIn-Device Coexistence (IDC) in 3GPP and, in other communicationtechnology with the exception of LTE, call interfering communicationtechnology (interfering CT).

Unlike the LTE/UMTS communication technology operating on variousfrequency bands, the other communication technology such as Bluetoothand WLAN operates on Industrial, Scientific and Medical band(24000-2483.5 MHz). Among the frequency bands for use in LTE/UMTScommunication technology, particularly, in the case of frequency band 4(2300-2400 MHz) and uplink part of frequency band 7 (2500-2570 MHz), thetransmission signal of one communication technology is detected as thereception signal of another communication technology so as to causesignificant interference problem. For example, when the WLAN useschannel 1 on the frequency band 40, the effect of interference becomesworse; and in the case that the mobile communication base station usesthe frequency band 7 and the WLAN uses channel 13 or 14, interferenceoccurs significantly.

When such effect occurs, it is preferred to hand the UE over to the bandwithout causing interference problem. This can be accomplished throughthe mutual operation between the UE and the eNB as follows.

1. IDC interference occurs on the current serving frequency

2. The UE sends the eNB a control message reporting occurrence of IDCinterference

3. The eNB instructs the UE to measure neighbor cells/frequencies forhandover

4. The UE reports measurement result to the eNB

5. Hands the UE over to another frequency based on the measurementreport

At this time, the UE may be handed over to an LTE cell on anotherfrequency or, if other LTE frequency is not available, to another radiotechnology (e.g. UMTS) cell.

In the case that the UE is handed over to the LTE cell, since the LTEeNB knows the UE undergoes IDC interference on the previous servingfrequency, it does not hand the UE to the frequency until the IDCinterference is resolved. If the IDC interference is resolved, the UEreports IDC interference resolution to the LTE eNB. Accordingly, it ispreferred to rule out the influence of the IDC interference in measuringthe frequency causing the IDC and reporting the measurement result.Meanwhile, in the case that the UE is handed over to another radiotechnology cell, since the other radio technology base station or radionetwork controller is not an LTE eNB, it does not know that the UEundergoes IDC interference on the LTE frequency. Accordingly, if the UEreports the measurement result with the exclusion of IDC interference,this may cause a problem of handing the UE over back to the LTEfrequency.

In the present invention, the current serving network performs LTEfrequency measurement differently depending on whether the currentserving network is an LTE network in order to overcome the aboveproblem.

In the case of measuring a frequency x, managing measurement result, andtriggering measurement result report; when the frequency x is an LTEfrequency and the IDC interference device (WLAN device, Bluetoothdevice, etc.) of the UE generates a signal causing interference to thefrequency x; if the current serving radio technology is the LTEtechnology (or the serving frequency is the LTE frequency or thefrequency band of the serving frequency is the LTE band), themeasurement scheme 1 is applied and, otherwise if the serving radiotechnology is not the LTE technology (or the serving frequency is notthe LTE frequency or the serving radio technology is non-LTE technology,e.g. UMTS (or serving frequency is the UMTS frequency or the frequencyband of the serving frequency is the UMTS band), the measurement scheme2 is applied.

FIG. 9 shows the UE operation.

In the following, the UE determines the measurement scheme for use inmeasuring neighboring frequencies (frequencies other than servingfrequency), e.g. Reference Signal Received Power (RSRP) or ReferenceSignal Received Quality (RSRQ).

Neighbor frequency measurement timing arrives at step 905. The UEdetermines whether the frequency to be measured is an LTE frequency atstep 910. If the frequency is not an LTE frequency, the UE performsmeasurement according to the legacy technology at step 915. If thefrequency is not an LTE frequency, the UE determines whether thefollowing condition is fulfilled at step 920.

[Condition]

Has IDC interference occurred on the LTE frequency, has IDC interferenceoccurrence been reported to the eNB, and has the eNB handed the UE overto another frequency band or configured DRX to the UE to resolve the IDCinterference (or is the UE capable of communicate data with the eNB inspite of the IDC interference or has the eNB provided a solution for theIDC interference problem)?

If the above condition is not fulfilled, the procedure goes to step 91.If the condition is fulfilled, the procedure goes to step 925 at whichthe UE determines whether the current serving frequency is an LTEfrequency. If so, this means that the eNB knows the IDC interferenceproblem of the UE and thus the UE applies the measurement scheme 1 atstep 930. If the current serving frequency is not an LTE frequency (butUMTS frequency), this means the base station or radio network controllerdoes not know the IDC interference problem of the UE and thus the UEapplies the measurement scheme 2 at step 935.

[Measurement Scheme 1]

The UE performs measurement periodically and, if there is no IDCinterference in the subframe to be measured, the measurement resultvalue is updated by filtering with only the instantaneous measurementvalue at the subframe in which no IDC interference exists withoutconsideration of the measurement result value at the subframe in whichIDC interference exists.

The filtered measurement result value is a weighted average value of theinstantaneous measurement values. For example, the measurement resultvalue filtered at the time n is the value obtained by summing the valueobtained by multiplying a predetermined weight to the instantaneousmeasurement result value at time n and the value obtained by multiplyinganother predetermined weight to the measurement result value filtered attime [n−1].

[Measurement Scheme 2]

The UE performs measurement periodically, updates the measurement valuefiltered with the instantaneous measurement result value acquiredwithout consideration of existence of IDC interference at themeasurement occasion, and determine whether to trigger measurementresult message based on the filtered measurement result value.

By reflecting the IDC interference to the measurement result, it ispossible to prevent the radio network controller from handing the UEover to the problematic LTE frequency.

[Another Measurement Scheme 2]

Like the measurement scheme 2, the UE selects the subframe forperforming instantaneous measurement and updates the filteredmeasurement result value. In the case of determining whether to triggerthe measurement report, however, the UE uses the value obtained apredetermined offset from the filtered measurement result value and alsoreport the measurement result with the value obtained by subtracting apredetermined offset from the filtered measurement result value. Thatis, the UE determines whether to trigger the measurement result messagebased on the value obtained by subtracting the offset from the filteredmeasurement result value. In the case that the measurement resultmessage is triggered, the UE reports the value obtained by subtractingthe offset from the filtered measurement result value other than thefiltered measurement result value.

By reporting the value poorer than the real channel condition, it ispossible to further reduce the probability of handover to the frequencyon which IDC interference exists.

Fourth Embodiment

When a plurality of serving cells is configured to a UE, Timing AdvanceGroups (TAGs) are configured to manage the uplink transmission timingsof the serving cell efficiently. A TAG is comprised of at least oneserving cell, and a UE is configured with at least one TAG. The servingcells belonging to a TAG share the same uplink transmission timing. TheTAG including the PCell is referred to as P-TAG and the TAG includingonly SCells is referred to as S-TAG.

The TAG performance is influenced by the RF frontend structure and bandcombination of the UE. Particularly, it may be possible or not toconfigure different TAG for the serving cells formed on the samefrequency band depending on the UE and frequency band. If the UE appliesindependent FFTs to the serving cells, it is possible to configuredifferent TAGs and, otherwise the one FTT is shared, only one TAG. Thenumber of TAGs a UE can support simultaneously depends on the number ofuplink transmission timings the UE can maintain at the same time.

At least according to the standard, one UE can support various types ofband combinations. For example, one UE may support four bandcombinations as follows.

Combination 1: two serving cells on band X

Combination 2: two serving cells on band Y

Combination 3: two serving cells on band X and one serving cell on bandY

Combination 4: one serving cell on band X and tow serving cells on bandY

Depending on the UE, the TA performance can differ significantly. Forexample, a UE does not support a plurality TAGs for combination 1 whileanother UE may supports a plurality TAGs. A UE may support one TAG onband X and on TAG on band Y, another UE may support two TAG on band Xand one TAG on band Y, and another UE may support two TAGs on band X andone TAG on band Y or TAG with one cell on band X and TAG with anothercell on band X and one cell on band Y.

In this way, it is possible to generate various combinations dependingon whether the serving cells of the same frequency band can be groupedinto different TAGs, whether the serving cells on different frequencybands can be grouped into the same TAG, or how many TAGs can be formedwith the serving cells on one frequency band.

It may be considered to use a signaling system accommodating allpossibilities when the UE reporting its TA capability to the eNB. Asshown in the above discussion, such approaches have a shortcoming ofcomplex signaling because all per-band combinations supportabilitieshave to be displayed.

The present embodiment proposes a method for reporting the TA capabilityof the UE using 1-bit information per band combination.

The UE indicates whether it supports basic TA capability using 1 bitcorresponding to each supported band combination. The basic TAcapability means predetermined TA capability which is likely to besupported in general in the current release. In this embodiment, thebasic TA capability indicates whether the corresponding band combinationis an intra-band combination or an inter-band combination.

Basic TA capability of intra-band combination: support 2 TAGs (i.e. theserving cells on the same band may be grouped into up to two TAGs)

Basic TA capability of inter-band combination: It is possible toconfigure one Tag per band and TAGs as many as the number of bands ofthe corresponding band combination.

For example, if it is indicated that the basic TA capability issupported for the band combinations below, the UE capability is asfollows.

Combination 1: two serving cells on band X—serving cells on band X canbe grouped into up to two TAGs (i.e. support up to 2 TAGs)

Combination 2: two serving cells on band Y—serving cell on band Y can begrouped into up to two TAGs (i.e. support up to 2 TAGs)

Combination 3: two serving cells on band X and one serving cell on bandY—cells on band X is grouped into one TAG and cell on band Y intoanother TAG (i.e. support up to 2 TAGs)

Combination 4: one serving cell on band X and two serving cells on bandY—cell on band X is grouped into one TAG and cells on band Y intoanother TAG (i.e. support up to 2 TAGs).

Combination 5: one serving cell on band X, one serving cell on band Y,one serving cell on band Z—cell on band X is grouped into one TAG, cellon band Y into another TAG, and cell on band Z into still another TAG(i.e. support up to 3 TAGs)

If it is indicated that the UE does not support basic TA capability fora band combination, this is one of the two meanings:

1. Do not support multiple TAs for the corresponding band combination or

2. supports the TA capability superior to the basic TA capability forthe corresponding band combination.

In the case of section 1, the UE does not report other information forthe corresponding band combination; and in the case of section 2, the UEreports additional capability for the corresponding band combination.For example, the additional capability may include at least one of theinformation indicating whether to support possibilities of thecombinations considered with all the cases whether the serving cells ondifferent bands can be grouped into a TAG and whether two or more TAGscan be configured per band.

FIG. 14 is a flowchart illustrating the UE operation according to thefourth embodiment of the present invention.

The UE receives a UE CAPABILITY ENQUIRY message at step 1405. If the UECAPABILITY ENQUIRY message is received, the procedure goes to step 1410.At step 1410, the UE checks the RAT type. If the RAT type is set toEUTRA, the procedure goes to step 1420 and, otherwise the RAT type isset to a value other than EUTRA, step 1415. At step 1415, the UEoperates according to the legacy technology.

The UE transmits a UE CAPABILITY INFORMATION message including its LTEcapability information at step 1420. The LTE capability informationincludes one or more band combination information about the bandcombinations it supports. The UE inserts 1-bit information indicatingwhether the basic TA capability is supported per band combinationinformation. The basic TA capability information is set to a value whichis determined depending on whether the corresponding band combinationincludes only one band or more. If the corresponding band combinationincludes only one band, the basic TA capability is the capability ofgrouping the serving cells on the corresponding band into up to X TAGs.That is, it is the capability of supporting X TAGs. Here, X can bedefined as the minimum value between the number of serving cellssupported in the band combination and a predetermined integer, e.g. 2.For example, if a band combination includes one band and up to 3 cellscan be configured, this means that the basic TA capability of the bandcombination supports 2 (minimum value 2) TAGs. If a band combinationincludes two or more bands, this means that the basic TA capabilitysupports one TAG per band.

For the band combination which is indicated to support the basic TAcapability, if the band combination does not support multiple TAGs, theUE adds no additional information and, otherwise the band combinationsupports the TA capability higher than the basic TA capability, addspredetermined addition information.

FIG. 19 shows inter-band combinations according to an embodiment of thepresent invention. A description is made of the basic TA capabilityaccording to an embodiment of the present invention in detail withreference to FIG. 19.

There may be various TAG capabilities applicable to different bandcombinations. Four TAG capabilities are exemplified below.

1. TAG capability example 1 (1905): only one TAG can be configured perband. It is impossible to configure a TAG including serving cells ondifferent bands.

2. TAG capability example 2 (1910): two or more TAGs can be configuredper band. It is impossible to configure a TAG including serving cells ondifferent bands.

3. TAG capability example 3 (1915): two or more TAG can be configuredper band, and it is possible to configure a TAG including serving cellson different bands.

4. TAG capability example 4 (1920): up to on TAG can be configured perband, and it is possible to configure a TAG including serving cells ondifferent bands.

As described above, it is not necessary to include the TAG capability 21910 and TAG capability example 3 1915 in the basic TA capability.However, it is preferred to include the TAG capability example 4 1920 inthe basic TA capability. This is because the TAG capability example 41920 includes the case of configuring a TAG with the serving cells onall bands. Accordingly, in this embodiment, the TAG capability examples1 and 4 are included in the basic TA capability and, in this case, thebasic TA capability is defined as follows.

1. basic TA capability of intra-band combination: it is possible toconfigure one or more TAGs in the corresponding band, and the maximumnumber of TAGs is identical with the number of serving cells configuredon the corresponding band.

2. basic TA capability of inter-band combination: it is possible toconfigure one or more TAGs in the corresponding band combination, andthe serving cells on the same band have to belong to the same TAG (orone TAG). The maximum number of TAGs is identical with the number ofbands of the corresponding band combination.

FIG. 20 is a diagram illustrating ‘supportedBandCombination’ 2005according to an embodiment of the present invention.

The supportedBandCombination 3005 which the UE reports to the networkincludes at least one band parameter 2010. The band information 2010includes a band indicator 2015 indicating the corresponding band number,one or more downlink bandwidth class informations 2020 and 2030, and oneor more uplink bandwidth class informations 2025 and 2030.

The bandwidth class informations 2020, 2030, 2025, and 2035 is ofexpressing the maximum aggregative bandwidth in the correspondingdirection (UL/DL) of the corresponding band and the number of servingcells together and can be defined in the form as shown in table 4.

TABLE 4 CA Bandwidth Aggregated Transmission Bandwidth Maximum ClassConfiguration number of CC A Aggregative bandwidth ≤20 1 B Aggregativebandwidth ≤20 2 C 20 < Aggregative bandwidth ≤ 40 2 D . . . . . . E . .. . . . F . . . . . .

For example, if the bandwidth class is set to B for a frequency band,the corresponding bandwidth class information indicates that up to twocarriers (or two serving cells) can be configured on the frequency bandand the sum of the bandwidths of the serving cells configured on thefrequency band is up to 20 MHz.

FIG. 21 shows the band combination information supported according to anembodiment of the present invention.

Since the TAG is related to uplink, it is assumed that the UE hasreported supportedBandCombination 2130 when limiting the discussion tothe uplink. The information 2130 includes a band parameter 2135 for band1 and another band parameter 2140 for band 5. The bandwidth class A 2110and bandwidth class C 2115 are supported for the uplink of band 1. Forexample, the UE supports one serving cells on band 1 and one servingcell on band 5 or two serving cells on band 1 and one serving cell onband 5 for uplink in the band combination of bands 1 and 5.

One supportedBandCombination 2145 may include two or more bandparameters 2105 and 2165 for the same band. That is, the UE maytransmits the information indicating of the support of another servingcell on band 1 simultaneously while it supports one serving cell onband 1. This is for reporting the UE capability in the case where theserving cell indicated by the bandwidth class 2160 of the first bandparameter 2150 and the serving cell indicated by the bandwidth class2175 of the second band parameter 2165 are not contiguous. Such acombination is referred to as non-contiguous intra-band combination. Thenon-contiguous intra-band combination indicates actually the intra-bandcombination. In view of information format, however, this is closer tothe inter-band combination. To the non-contiguous intra-bandcombination, the basic TA combination of the inter-band combination,other than of the intra-band combination, is applied. If a bandparameter of a band combination is called band entry, the basic TAcapability can be expressed as follows.

1. basic TA capability for band combination composed of one band entry:one or more TAGs can be formed in the corresponding band entry, and themaximum number of TAGs is identical with the number of serving cellsconfigured for the corresponding band entries

2. basic TA capability for band combination composed of multiple bandentries: one or more TAG can be configured in the corresponding bandcombination, and the serving cells in the same band have to belong tothe same TAG (or one TAG). The maximum number of TAGs is identical withthe number of band entries of the corresponding band combination.

FIG. 22 is a diagram illustrating the structure of thesupportedBandCombination according to an embodiment of the presentinvention.

The ‘number of serving cells configured to corresponding band entries’denotes the number of CCs (or number of serving cells) indicated by thehighest class (class having largest number of CC) among the bandwidthclass for uplink when the band entry includes a plurality bandwidthclasses. Here, if it is said the bandwidth class C is higher than thebandwidth class A, this means that the aggregative bandwidth of thebandwidth class C is broader or, although the aggregative bandwidths ofthe bandwidth classes C and A are identical with each other, the maximumnumber of CCs of the bandwidth class C is greater. For example, when aUE reports the supportedBandCombination 2205 comprised of one band entry2207, if the 1 bit representing the basic TA capability supportabilityis set to YES, this means that the UE supports one or more TAGs for theband combination and the maximum number of TAGs is 2. The band entry2207 includes two uplink bandwidth classes 2210 and 2215 and twodownlink bandwidth classes 2220 and 2225, and the UE determines themaximum number of TAGs based on the bandwidth class C as the highestclass among the uplink bandwidth classes.

The UE may transmit its capability report including multiplesupportedBandCombination informations and 1 bit indicating whether itsupports the basic TA capability per supportedBandCombination. If thesupportedBandCombination is comprised of one band entry, the 1 bit maybe set to YES or NO depending on whether the UE supports the ‘basic TAcapability for band combination composed of one band entry.’

If the supportedBandCombination is comprised of two or more bandentries, the 1 bit may be set to YES or NO depending on whether the UEsupports the ‘basic TA capability for band combination comprised ofmultiple band entries.’

The eNB determines the TA capability supported by the UE for the bandcombination based on the information indicating whether thesupportedBandCombination reported by the UE is composed of one bandentry or multiple band entries and the value of 1 bit indicating whetherthe basic TA capability is supported.

The following embodiment relates to an efficient cell (re)selectionmethod of the UE. This embodiment is directed to the 3^(rd) GenerationPartnership Project (3GPP) Long Term Evolution (LTE)/LTE-Advanced(LTE-A) system environment.

FIGS. 16A and 16B are diagrams illustrating a configuration of the 3GPPLTE system according to an embodiment of the present invention.

The radio access network of the LTE system includes evolved Node Bs(eNBs) 3105, 3110, 3115, and 3120, a Mobility Management Entity (MME)3125, and a Serving-Gateway (S-GW) 3130. The User Equipment(hereinafter, referred to as UE) 3135 connects to an external networkvia the eNBs 3105, 3110, 3115, and 3120 and the S-GW 130. The eNBs 3105,3110, 3115, and 3120 correspond to the legacy node Bs of the UMTSsystem. The eNB 3105 is connected with the UE 3135 and is responsiblefor functions more complicated as compared to the legacy node B. In theLTE system, all the user traffic services including real time servicessuch as Voice over Internet Protocol (VoIP) are provided through ashared channel and thus there is a need of a device to schedule databased on the state information collected form the UEs, the eNBs 3105,3110, 3115, and 3120 being responsible for such functions. Typically,one eNB controls a plurality of cells. In order to secure the data rateof up to 100 Mbps, the LTE system adopts Orthogonal Frequency DivisionMultiplexing (OFDM) as a radio access technology. Also, the LTE systemadopts Adaptive Modulation and Coding (AMC) to determine the modulationscheme and channel coding rate in adaptation to the channel condition ofthe UE. The S-GW 3130 is an entity to provide data bearers andestablishes and releases data bearers under the control of the MME 3125.The MME 125 is responsible for various control functions and may beconnected to plural eNBs 3105, 3110, 3115, and 3125.

FIGS. 16A and 16B are flowcharts illustrating the cell reselectionprocedure according to an embodiment of the present invention.Hereinafter, FIGS. 16A and 16B are collectively referred as FIG. 3.FIGS. 16A and 16B show an exemplary inter-frequency/Radio AccessTechnology (RA cell (re)selection procedure of the UE in the RadioResource Control (RRC) idle mode. The UE in the RRC idle mode is the UEin the state without RRC connection with the eNB controlling the cell.The UE in the RRC idle mode receives some shared channels such as pagingperiodically and reselects suitable cell depending on the channelenvironment to guarantee the UE mobility. The detailed operation of theUE in the RRC idle mode of the 3GPP system is specified in the 3GPPTS36.304 ‘E-UTRAN UE Procedure in idle mode’ and TS25.304 ‘UTRAN UEProcedure in idle mode.’

In FIGS. 16A and 16B, the blocks saying ‘maintain’ means that the UEremains in the current serving cell without cell reselection to aneighbor LTE frequency/RAT frequency. In FIG. 16B, the blocks saying‘error handling’ means that the UE performs error handling caused byreceipt of unexpected information.

The UE in the RRC idle mode starts measurement on neighbor RATs at step3301. The UE monitors the System Information Block 3 (SIB3) broadcastwithin the cell to check whether ThreshServingLowQ is received at step3311. The ThreshServingLowQ is a threshold value for determining thechannel state Squal of the current LTE serving cell as a condition toreselect a neighbor LTE frequency or RAT with priority lower than thatof the current LTE serving frequency. The Squal is described later indetail. If the ThreshServingLowQ is not signaled/provided through theSIB3, the procedure goes to step 3321 at which the UE calculates Srxlevvalues for the LTE serving cell and the neighbor frequency/RAT cellswhich is received through the system information blocks. The Srxlevdenotes Cell selection Rx level value (dB) and calculated with equation(1). However, the Srxlev for CDMA2000 is calculated with equation (2)other than equation (1).

Srxlev=Q _(rxlevmeas)−(Q _(rxlevmin) +Q_(rxlevminoffset))−Pcompensation  (1)

Srxlev=−FLOOR(−2×10×log 10 Ec/Io) in units of 0.5 dB (with Ec/Ioreferring to the value measured from the evaluated cell)  (2)

Here, Q_(rxlevmeas) denotes the downlink reception power as a valueactually measured on the Downlink (DL) reference channel by the UE.Q_(rxlevmin) denotes the minimum required downlink reception power forselecting the corresponding cell. Q_(rxlevminoffset) denotes an offsetvalue added to Q_(rxlevmin) only when the UE located in the VisitedPublic Land Mobile Network (VPLMN) searches for higher priority PLMN.Pcompensation denotes an offset value to balance the uplink and downlinkchannel states in consideration of the uplink channel condition. Table 5explains the respective parameters.

TABLE 5 Srxlev Cell selection RX level value (dB) Q_(rxlevmeas) Measuredcell RX level value (RSRP) Q_(rxlevmin) Minimum required RX level in thecell (dBm) Q_(rxlevminoffset) Offset to the signaled Q_(rxlevmin) takeninto account in the Srxlev evaluation as a result of a periodic searchfor a higher priority PLMN while camped normally in a VPLMN [5]Pcompensation max(P_(EMAX) − P_(PowerClass), 0) (dB) P_(EMAX) Maximum TXpower level an UE may use when transmitting on the uplink in the cell(dBm) defined as P_(EMAX) in [TS 36.101] P_(PowerClass) Maximum RFoutput power of the UE (dBm) according to the UE power class as definedin [TS 36.101]

The DL reference channel for channel measurement may vary depending onthe system. In the case of the E-UTRAN system, the UE measures ReferenceSignal (RS) channel. In the case of the UTRAN FDD system, the UEmeasures the Common Pilot Channel (CPICH). In the case of the UTRAN TDDsystem, the UE measures the Primary Common Control Physical Channel(P-CCPCH). In the case of the GERAN system, the UE measures theBroadcast Channel (BCCH).

The Q_(rxlevmeas) of the LTE serving cell may be acquired using theReference Signal Received Poser (RSRP). The Q_(rxlevmeas) of theneighbor UTRAN FDD/TDD system cell may be acquired using the ReceivedSignal Code Power (RSCP). The Q_(rxlevmeas) of the neighbor GERAN systemcell may be acquired using the Received Signal Strength Indicator(RSSI). The respective measurement parameters are specified in the 3GPPTS36.214 ‘E-UTRA Physical Layer Measurements’ and TS25.215 ‘PhysicalLayer—Measurements (FDD).’

The UE determines whether the priority of the measurement targetneighbor LTE frequency/RAT frequency is greater than that of the servingLTE frequency at step 3331. The priority information indicates thefrequency as the target for cell reselection with priority. The priorityinformation may be acquired from the system information broadcast in theserving LTE cell or UE-specific message (e.g. RRC Connection Release)when the UE is in the RRC connected state. If the priority of themeasurement target neighbor LTE frequency/RAT frequency is greater thanthat of the serving LTE frequency, the procedure goes to step 3333.Otherwise if the priority of the measurement target neighbor LTEfrequency/RAT frequency is not greater than that of the serving LTEfrequency, the procedure goes to step 3341.

At step 3333, the UE determines whether the Srxlev of the neighbor LTEfrequency/RAT frequency cell is greater than ThreshX,HighP during theTreselection timer period. If the Srxlev of the neighbor LTEfrequency/RAT frequency cell is greater than ThreshX,HighP during theTreselection timer period, the procedure goes to step 3336. If theSrxlev of the neighbor LTE frequency/RAT frequency cell is not greaterthan ThreshX,HighP during the Treselection timer period, the currentserving cell is maintained and the cell reselection procedure ends.

At step 3336, the UE determines whether 1 second has elapsed since theUE camp-on to the current serving cell. If 1 second has elapsed sincethe camp-on to the current serving cell, the procedure goes to step 3339at which the UE performs cell reselection to the corresponding neighborLTE frequency/RAT frequency cell. Otherwise if 1 second has not elapsed,the UE remains in the current cell. The Treselection timer value to beapplied to the neighbor LTE frequency/RAT frequency and theThreshX,HighP Srxlev comparison threshold may be received through thesystem information broadcast in the serving LTE cell.

If the priority of the measurement target neighbor LTE frequency/RATfrequency is not greater than that of the serving LTE frequency at step3331, the procedure goes to step 3341. At step 3341, the UE determinesi) whether the Srxlev of the neighbor LTE frequency/RAT frequency cellis greater than the ThreshX,LowP and ii) whether the Srxlev of thecurrent LTE frequency serving cell is less than the ThreshServing,LowP.If the two conditions i) and ii) are fulfilled, the procedure goes tostep 3336. Otherwise if the two conditions i) and ii) are not fulfilled,the cell reselection to the neighbor LTE frequency/RAT frequency celldoes not occurs.

If the ThreshServingLowQ is signaled/provided through the SIB3 at step3311, the procedure goes to step 3361. At step 3361, the UE calculatesthe Squal of the serving cell and the Squal of the neighbor LTEfrequency/UTRAN FDD frequency cell using the UE's measurement result andthe system information broadcast in the serving cell. If the neighborRAT is a UTRAN TDD or GERAN or CDMA2000 system, the Srxlev iscalculated.

The Squal denotes the Cell selection quality value (dB) and may becalculated using equation (3).

Squal=Q _(qualmeas)−(Q _(qualmin) +Q _(qualminoffset))  (3)

Here, Q_(qualmeas) denotes the ratio between received signal strength ofthe DL RS channel and the total noise that are measured actually by theUE, Q_(qualmin) denotes the minimum signal-to-noise ratio level requiredfor selecting the corresponding cell, and Q_(qualminoffset) denotes athreshold value which is added to Q_(qualmin) only when the UE in theVPLMN searches for the PLMN with the higher priority. The respectiveparameters are explained in table 6.

TABLE 6 Squal Cell selection quality value (dB) Q_(qualmeas) Measuredcell quality value (RSRQ) Q_(qualmin) Minimum required quality level inthe cell (dB) Q_(qualminoffset) Offset to the signaled Q_(qualmin) takeninto account in the Squal evaluation as a result of a periodic searchfor a higher priority PLMN while camped normally in a VPLMN [5]

The Q_(qualmeas) of the serving LTE cell and neighbor LTE frequency cellare acquired using the Reference Signal Received Quality (RSRQ). TheQqualmeas of the neighbor UTRAN frequency cell is acquired using Ec/No.The Ec/No is acquired using RSCP/RSSI. The RSSI stands for ReceivedSignal Strength Indicator. The RSRQ is specified in the 3GPP TS36.214‘E-UTRA Physical Layer Measurements.’ The Ec/No is specified in the 3GPPTX25.215 ‘Physical Layer—Measurements (FDD).’

The UE determines whether the priority of the neighbor LTE frequency/RATfrequency as a measurement target is higher than that of the serving LTEfrequency at step 3371. The UE selects the frequency for cellreselection based on the priority information. The priority informationis received through the system information broadcasted in the servingLTE cell or a UE-specific message, e.g. RRC Connection Release, when theUE in the RRC Connected state.

If the priority of the neighbor LTE frequency/RAT frequency as ameasurement target is higher than that of the serving LTE frequency, theprocedure goes to step 3373. Otherwise if the priority of the neighborLTE frequency/RAT frequency as a measurement target is not higher thanthat of the serving LTE frequency, the procedure goes to step 3391.

At step 3373, the UE determines whether the corresponding neighborfrequency is a neighbor LTE frequency and whether the neighbor RATfrequency is a UTRAN FDD system. If the corresponding neighbor frequencyis a neighbor LTE frequency or whether the neighbor RAT frequency is aUTRAN FDD system, the procedure goes to step 3376. Otherwise if neitherthe corresponding neighbor frequency is a neighbor LTE frequency nor theneighbor RAT frequency is a UTRAN FDD system, the procedure goes to step3383.

At step 3376, the UE determines whether the Squal of the neighbor LTEfrequency/UTRAN FDD frequency cell is greater than the ThreshX,HighQduring the Treselection timer period. If the Squal of the neighbor LTEfrequency/UTRAN FDD frequency cell is greater than the ThreshX,HighQduring the Treselection timer period, the procedure goes to step 3379.Otherwise if the Squal of the neighbor LTE frequency/UTRAN FDD frequencycell is not greater than the ThreshX,HighQ during the Treselection timerperiod, the cell reselection procedure ends.

The UE determines whether 1 second has elapsed since the camp-on to thecurrent serving LTE cell at step 3379. If 1 second has elapsed since thecamp-on to the current serving LTE cell, the procedure goes to step 3381at which the UE performs cell reselection to the corresponding neighborLTE frequency/UTRAN FDD frequency cell. Otherwise if 1 second has notelapsed since the camp-on to the current serving cell, the UE remains inthe current cell and ends the cell reselection procedure.

At step 3383, the UE determines whether the neighbor RAT frequency is aUTRAN TDD/GERAN/CDMA2000. If the neighbor RAT is a UTRANTDD/GERAN/CDMA2000, the procedure goes to step 3386. Otherwise if theneighbor RAT is not a UTRAN TDD/GERAN/CDMA2000, this means an error hasoccurred and this the UE performs and error handling operation. At step3386, the UE determines whether the Srxlev of the neighbor RAT frequencycell is greater than the ThreshX,HighP during the Treselection timerperiod. If the Srxlev of the neighbor RAT frequency cell is greater thanthe ThreshX,HighP during the Treselection timer period, the proceduregoes to step 3379. Otherwise if the Srxlev of the neighbor RAT frequencycell is not greater than the ThreshX,HighP during the Treselection timerperiod, the UE remains in the current cell and ends the cell reselectionprocedure.

The UE determines whether the corresponding neighbor frequency is aneighbor LTE frequency or whether the neighbor RAT frequency is a UTRANFDD system at step 3391. If the corresponding neighbor frequency is aneighbor LTE frequency or if the neighbor RAT frequency is a UTRAN FDDsystem, the procedure goes to step 3393. Otherwise if the correspondingneighbor frequency is not a neighbor LTE frequency or if the neighborRAT frequency is not a UTRAN FDD system, the procedure goes to step3396.

At step 3393, the UE determines whether the Squal of the neighbor LTEfrequency/UTRAN FDD frequency cell is greater than the ThreshX,LowQ andthe Squal of the current LTE frequency serving cell is less than theThreshServing,LowQ during the Treselection timer period. If the Squal ofthe neighbor LTE frequency/UTRAN FDD frequency cell is greater than theThreshX,LowQ and the Squal of the current LTE frequency serving cell isless than the ThreshServing,LowQ during the Treselection timer period,the procedure goes to step 3379. Otherwise if the conditions of step3393 are not fulfilled, the UE remains in the current cell and ends thecell reselection procedure.

At step 3396, the UE determines whether the neighbor RAT frequency is aUTRAN TDD/GERAN/CDMA2000 system. If the neighbor RAT frequency is aUTRAN TDD/GERAN/CDMA2000 system, the procedure goes to step 3399.Otherwise if the neighbor RAT frequency is not a UTRANTDD/GERAN/CDMA2000 system, this means an error has occurred and thus theUE performs an error handling operation.

At step 3399, the UE determines whether the Srxlev of the neighbor LTEfrequency/UTRAN TDD/GERAN/CDMA2000 frequency cell is greater than theThreshX,LowP and the Srxlev of the current LTE frequency serving cell isless than the ThreshServing,LowP during the Treselection timer period.If the Srxlev of the neighbor LTE frequency/UTRAN TDD/GERAN/CDMA2000frequency cell is greater than the ThreshX,LowP and the Srxlev of thecurrent LTE frequency serving cell is less than the ThreshServing,LowPduring the Treselection timer period, the procedure goes to step 3379.Otherwise if the conditions of step 3399 are not fulfilled, the cellreselection to the neighbor LTE frequency/RAT frequency cell does notoccurs.

In the 3GPP, discussions made of a frequency priority-based cellselection method for preventing the UE in the idle mode from reselectingspecific frequency band or RAT when the corresponding frequency band orRAT undergoes congestion or the eNB undergoes processing overload.

FIG. 17 is a signal flow diagram illustrating a de-prioritizationprocedure according to an embodiment of the present invention. In FIG.17, the system includes a UE 3501 in the idle mode and an eNB 3511 whichcontrols the cell on which the UE has camped.

The UE 3501 in the idle mode sends the eNB 3511 an RRC ConnectionRequest message to establish an RRC connection with the eNB 3511 at step3521. For example, if data transmission is required, the UE 3501 may tryto establish an RRC connection.

Upon receipt of the RRC Connection Setup Request message at step 3521,the eNB 3511 determines the congestion level of the frequency band ofthe cell as well as the cell itself or the RAT of the cell (here, thecurrent serving cell system is assumed as the LTE system). If thecorresponding frequency band or the RAT is congested on the whole, theeNB 3511 sends the UE 3501 an RRC Connection Reject message. The RRCConnection Reject message includes a priority down indicator forlowering the priority of the current frequency and/or RAT and a timerfor the validity of the indicator.

If the Connection Reject message is received, the UE 3501 starts thetimer set to a predetermined value which is included in the ConnectionReject message at step 3541. The UE 3501 decreases the priority value ofthe frequency and/or RAT to the lowest level (or a predetermined lowvalue) to perform cell reselection until the timer expires. In FIG. 17,it is assumed that the timer value is signaled through the ConnectionReject message. According to an alternative embodiment, no timer valueis carried in the Connection Reject or other messages, but apredetermined value is used. By decreasing the priority of a specificfrequency or RAT undergoing congestion under the control of the eNB, theUE 3501 which receives the signal performs cell reselection to accessother frequency or RAT cell so as to overcome the cell/eNB congestionproblem.

FIG. 18 is a flowchart illustrating a de-prioritization procedure of theUE according to an embodiment of the present invention. The UE 305receives the information indicating de-prioritization of the priority ofa specific frequency (frequency of the cell in which the RRC ConnectionReject message has been transmitted) or the whole frequency of the RATof the corresponding cell through the RRC Connection Reject message atstep 3701. The UE 3501 may inform the eNB 3511 whether to de-prioritizethe current frequency or the whole frequency of the RAT which includesthe current frequency.

If the priority De-Prioritization indication information is received,the UE 3501 starts the de-prioritization timer, stores the informationon the original priority of the corresponding frequency and/or wholefrequency of the corresponding RAT, and changes (adjusts) the priorityof the corresponding frequency and/or the whole frequency of thecorresponding RAT to the lowest priority (or a low value) arbitrarily atstep 3711. Although the embodiment of FIG. 18 is directed to a casewhere the de-prioritization timer starts first at step 3711, the timermay start last at step 3711 in an alternative embodiment.

The UE determines whether the timer has expired at step 3721. If thetimer has expired, the procedure goes to step 3731. At step 3731, the UErecovers the original priority value stored at step 3711 and applies therecovered priority to the corresponding frequency and/or the wholefrequency of the RAT.

If the timer has not expired, the procedure goes to step 3741. At step3741, the UE determines whether the RRC Connection is released on thecorresponding frequency/RAT to which the priority de-prioritization isbeing applied. For example, it is such a case that the UE performs cellreselection to access another frequency/RAT cell and establish an RRCconnection thereto due to the de-prioritization of the correspondingfrequency/RAT but the network hands the UE over to correspondingfrequency/RAT to which the priority de-prioritization is being appliedand releases the RRC connection.

If the RRC connection to the corresponding frequency/RAT to which thepriority de-prioritization is being applied is released at step 3741,the procedure goes to step 3751. Otherwise, the procedure goes back tostep 3721 to determine whether the timer has expired. The UE 3501determines whether the frequency de-prioritization is applied to apartial frequency band of the whole RAT frequency band at step 3751. Ifthe frequency de-prioritization is applied to a partial frequency bandof the whole RAT frequency band, the procedure goes to step 3761. Atstep 3761, the UE 3501 stops the de-prioritization timer for thecorresponding frequency and applies/recovers the original priority valuestored at step 3711 to the frequency. In the embodiment, it is assumedthat the de-prioritization timer runs per frequency. If one timer isused for all frequencies, the de-prioritization timer stops only when itis applied to one frequency and, in other cases, the de-prioritizationtimer keeps running.

If the frequency de-prioritization is not applied to a partial frequencyband of the whole RAT frequency band at step 3751, the procedure goes tostep 3771. At step 3771, the UE 3501 determines whether the priorityde-prioritization is being applied to the whole frequency of the RATwhich includes the corresponding frequency. If the priorityde-prioritization is being applied to the whole frequency of the RATwhich includes the corresponding frequency, the procedure goes to step3781. At step 3781, the UE 3501 stops the de-prioritization timer forthe corresponding RAT and applies/recovers the original priority valuestored per frequency of the RAT at step 3711.

If the priority de-prioritization is not being applied to the wholefrequency of the RAT which includes the corresponding frequency, thismeans an erroneous situation and thus the procedure goes to step 3791.If the per-frequency priority information stored at step 3711 does notinclude the whole frequency of the RAT, this is also an erroneoussituation and thus the procedure goes to step 3791. At step 3791, the UE3501 perform error handling process on the unexpected error.

FIG. 10 is block diagram illustrating a configuration of the UEaccording to an embodiment of the present invention.

As shown in FIG. 10, the UE according to an embodiment of the presentinvention includes a transceiver 1005, a controller 1010, amultiplexer/demultiplexer 1015, a control message processor/RRCcontroller 1035, and upper layer processor 1020 and 1025.

The transceiver 1005 is responsible for receiving data and predeterminedcontrol signal through a downlink channel of the serving cell andtransmitting data and predetermined control signals through an uplinkchannel. In the case that a plurality of serving cells is configured,the transceiver 1005 transmits and receives data and control signalsthrough the plural serving cells.

The multiplexer/demultiplexer 1015 is responsible for multiplexing datagenerated by the upper layer processors 1020 and 1025 and the controlmessage processor 1030 or demultiplexing data received by thetransceiver 1005 to deliver the demultiplexed data to the upper layerprocessors 1020 and 1025 and the control message processor 1030.

The control message processor 1030 processes the control messagereceived from the eNB and takes a necessary action.

The upper layer processor 1020 and 1025 is established per service. Theupper layer processors 1020 and 10250 process the data generated in theuser service such as File Transfer Protocol (FPT) and Voice overInternet Protocol (VoIP) and transfers the processed data to themultiplexer/demultiplexer 1015 or processes the data from themultiplexer/demultiplexer 1015 and delivers the processed data to theupper layer service applications.

The controller 1010 checks the scheduling command, e.g. uplink grants,received through the transceiver 1005 and controls the transceiver 1005and the multiplexer/demultiplexer 1015 to perform uplink transmissionwith appropriate transmission resource at an appropriate timing.

FIG. 11 is a block diagram illustrating a configuration an eNB accordingto an embodiment of the present invention, and the eNB includes atransceiver 1105, a controller 1110, a multiplexer/demultiplexer 1120, acontrol message processor/RRC controller 1135, upper layer processors1125 and 1130.

The transceiver 1105 is responsible for transmitting data andpredetermined control signal through a downlink channel and receivingdata and predetermined control signals through an uplink channel. In thecase that a plurality of carriers is configured, the transceiver 1105transmits and receives data and control signals through the pluralcarriers.

The multiplexer/demultiplexer 1120 is responsible for multiplexing datagenerated by the upper layer processors 1125 and 1130 and the controlmessage processor/RRC controller 1135 or demultiplexing data received bythe transceiver 1105 to deliver the demultiplexed data to the upperlayer processors 1125 and 1130, the control message processor/RRCcontroller 1135, and the controller 1110. The control messageprocessor/RRC controller 1135 processes the control message transmittedby the UE to take a necessary action or generates a control messageaddressed to the UE to the lower layer.

The upper layer processor 1125 (or 1130) is established per service,processes the data to be transmitted to the S-GW or another eNB into RLCPDU and transfers the RLC PDU to the multiplexer/demultiplexer 1120, andprocesses the RLC PDU from the multiplexer/demultiplexer 1120 into PDCPSDU to be transmitted to the S-GW or another eNB.

The scheduler 1115 allocates transmission resource to the UE at anappropriate timing in consideration of the buffer state and channelcondition of the UE and processes the signal transmitted form the UE orto be transmitted to the UE by means of the transceiver 1105.

The controller 1110 controls the transceiver 1105 to receive the channelstate information transmitted by the UE.

It is to be appreciated that those skilled in the art can change ormodify the embodiments without departing the technical concept of thisinvention. Accordingly, it should be understood that above-describedembodiments are essentially for illustrative purpose only but not in anyway for restriction thereto. Thus the scope of the invention should bedetermined by the appended claims and their legal equivalents ratherthan the specification, and various alterations and modifications withinthe definition and scope of the claims are included in the claims.

Although preferred embodiments of the invention have been describedusing specific terms, the specification and drawings are to be regardedin an illustrative rather than a restrictive sense in order to helpunderstand the present invention. It is obvious to those skilled in theart that various modifications and changes can be made thereto withoutdeparting from the broader spirit and scope of the invention.

What is claimed is:
 1. A method by a terminal in a communication system,the method comprising: receiving, from a base station, a first messagerelated to a capability of the terminal; generating a second messagerelated to capability information of the terminal, wherein the secondmessage includes first information on a band list and second informationindicating whether a multiple timing advance is supported; andtransmitting, to the base station, the second message, wherein, in casethat a band combination related to the band list is comprised of morethan one band entry, the second information indicates whether differenttiming advances on different band entries are supported.
 2. The methodof claim 1, wherein, in case that the band combination related to theband list is comprised of one band entry, the second informationindicates whether different timing advances across cells related to theband list are supported.
 3. The method of claim 1, wherein the secondinformation is indicated by an 1 bit indicator, wherein, in case thatthe band combination related to the band list is comprised of more thanone band entry, the band combination relates to an inter-band bandcombination or an intra-band non-contiguous band combination, andwherein, in case that the band combination related to the band list iscomprised of more than one band entry, the band combination relates toan intra-band contiguous band combination.
 4. The method of claim 1,further comprising: identifying whether the first message includes aspecific radio access technology (RAT) type, wherein the firstinformation and the second information are generated for the secondmessage.
 5. The method of claim 1, wherein the first message includesterminal capability enquiry message, and wherein the second messageincludes terminal capability information message.
 6. A terminal in acommunication system, the terminal comprising: a transceiver; and acontroller coupled with the transceiver and configured to: receive, froma base station, a first message related to a capability of the terminal,generate a second message related to capability information of theterminal, wherein the second message includes first information on aband list and second information indicating whether a multiple timingadvance is supported, and transmit, to the base station, the secondmessage, wherein, in case that a band combination related to the bandlist is comprised of more than one band entry, the second informationindicates whether different timing advances on different band entriesare supported.
 7. The terminal of claim 6, wherein, in case that theband combination related to the band list is comprised of one bandentry, the second information indicates whether different timingadvances across cells related to the band list are supported.
 8. Theterminal of claim 6, wherein the second information is indicated by an 1bit indicator, wherein, in case that the band combination related to theband list is comprised of more than one band entry, the band combinationrelates to an inter-band band combination or an intra-bandnon-contiguous band combination, and wherein, in case that the bandcombination related to the band list is comprised of more than one bandentry, the band combination relates to an intra-band contiguous bandcombination.
 9. The terminal of claim 6, wherein the controller isfurther configured to identify whether the first message includes aspecific radio access technology (RAT) type, wherein the firstinformation and the second information are generated for the secondmessage.
 10. The terminal of claim 6, wherein the first message includesterminal capability enquiry message, and wherein the second messageincludes terminal capability information message.
 11. A method by a basestation in a communication system, the method comprising: transmitting,to a terminal, a first message related to a capability of the terminal;and receiving, from the terminal, a second message related to capabilityinformation of the terminal, wherein the second message includes firstinformation on a band list and second information indicating whether amultiple timing advance is supported, wherein, in case that a bandcombination related to the band list is comprised of more than one bandentry, the second information indicates whether different timingadvances on different band entries are supported.
 12. The method ofclaim 11, wherein, in case that the band combination related to the bandlist is comprised of one band entry, the second information indicateswhether different timing advances across cells related to the band listare supported.
 13. The method of claim 11, wherein the secondinformation is indicated by an 1 bit indicator, wherein, in case thatthe band combination related to the band list is comprised of more thanone band entry, the band combination relates to an inter-band bandcombination or an intra-band non-contiguous band combination, andwherein, in case that the band combination related to the band list iscomprised of more than one band entry, the band combination relates toan intra-band contiguous band combination.
 14. The method of claim 11,wherein the first information and the second information are generatedfor the second message, in case that a specific radio access technology(RAT) type information is included in the first message.
 15. The methodof claim 11, wherein the first message includes terminal capabilityenquiry message, and wherein the second message includes terminalcapability information message.
 16. A base station in a communicationsystem, the base station comprising: a transceiver; and a controllercoupled with the transceiver and configured to: transmit, to a terminal,a first message related to a capability of the terminal, and receive,from the terminal, a second message related to capability information ofthe terminal, wherein the second message includes first information on aband list and second information indicating whether a multiple timingadvance is supported, wherein, in case that a band combination relatedto the band list is comprised of more than one band entry, the secondinformation indicates whether different timing advances on differentband entries are supported.
 17. The base station of claim 16, wherein,in case that the band combination related to the band list is comprisedof one band entry, the second information indicates whether differenttiming advances across cells related to the band list are supported. 18.The base station of claim 16, wherein the second information isindicated by an 1 bit indicator, wherein, in case that the bandcombination related to the band list is comprised of more than one bandentry, the band combination relates to an inter-band band combination oran intra-band non-contiguous band combination, and wherein, in case thatthe band combination related to the band list is comprised of more thanone band entry, the band combination relates to an intra-band contiguousband combination.
 19. The base station of claim 16, wherein the firstinformation and the second information are generated for the secondmessage, in case that a specific radio access technology (RAT) typeinformation is included in the first message.
 20. The base station ofclaim 16, wherein the first message includes terminal capability enquirymessage, and wherein the second message includes terminal capabilityinformation message.